Two-degrees-of-freedom vortex-induced vibration of cylinders covered with hard marine fouling. (1st November 2022)

• Record Type: Journal Article
• Authors: Ashrafipour, H.; Zeinoddini, M.; Tamimi, V.; Rashki, M.R.; Jadidi, P.
• Is Part Of: International journal of mechanical sciences. Volume 233(2022)
• Publication Date: 2022-11-01
• Subjects: Vortex-induced vibration -- Marine fouling -- Two-degree-of-freedom system -- Circular cylinder -- Poison cluster process; Mechanical engineering -- Periodicals; Génie mécanique -- Périodiques; Mechanical engineering; Maschinenbau; Mechanik; Zeitschrift; Periodicals; 621.05
• DOI: 10.1016/j.ijmecsci.2022.107624
• Languages: English
• ISSNs: 0020-7403

Abstract

Abstract: Marine fouling quickly covers the submerged surfaces of the man-made structures and affects the flow regime around them. Many important studies have already been conducted on the Vortex-Induced Vibration (VIV) of bluff bodies, but the two-Degree-of-Freedom (2-DoF) VIV of marine-fouled cylinders has received no previous attention. The current towing tank experimental study tries to fill this gap in the context of mechanical sciences. A Poisson Cluster Process (PCP) is used to model aggregated spatial distributions of artificial marine fouling on test cylinders. The Reynolds number ranges between 6.4 × 10 3 and 5.2 × 10 4 . The results show that in the fouling presence, the super-upper branch disappears from the 2-DoF VIV response of the cylinders. The maximum oscillation amplitudes in the in-line and cross-flow DoFs are reduced up to 37% and 50%, respectively, as compared to those of the smooth cylinder. Marine fouling moderately reduces the maximum lift force coefficient, whereas remarkably decreases the maximum drag force coefficient, the "lock-in" range, the lower branch length, and the reduced velocity ( U ∗ ) marking the beginning of the lower branch. The highest mitigation occurs with the most sparsely marine-fouled cylinder examined (33% coverage). The aforementioned fouling effects generally reduce as the fouling coverage ratio increases. Graphical abstract: Highlights: The paper reports results of first experiment on 2-DoF VIV of marine-fouled cylinders. Hard marine fouling significantly suppresses the maximum VIV amplitude in both DoFs. The fouling more strongly affects the VIV response of a 2-DoF system than a 1-DoF one. The super-upper branch disappears in 2-DoF VIV responses of marine-fouled cylinders. The best VIV suppression occurs in a test cylinder with the lowest fouling coverage.